Hereditary hemophilias are X-linked inherited bleeding disorders defined as deficiencies of the coagulation factors VIII or IX. They are characterized by easy to provoke or spontaneous bleeding. HIV infection in hemophilic patients is a risk factor for the reduction of CD4+ T cells. There is no information regarding the cellular immune function in HIV-negative patients with hemophilia. To evaluate the number of lymphocyte subsets in adult patients with hemophilia A or B as compared with healthy donors. 39 Adult hemophilics and 27 healthy donors were included. Lymphocyte subsets [CD4 and CD8 T cells, natural killer cells, natural killer T (NKT) cells, invariant NKT (iNKT) cells, gamma–delta T (γδT) cells, type 1 and 2 dendritic cells, CD14 monocytes, CD4 and CD8 regulatory T cells (Tregs), and B cells], were analyzed by flow cytometry. A significant decrease of CD4+ T lymphocytes, γδT cells, iNKT cells, CD4+ and CD8+ Tregs was observed in patients with hemophilia. Those patients having factor VIII inhibitor had the lowest CD4+ Treg and CD8+ Treg counts. CD14 monocytes were increased, as well as iNKT and type 2 dendritic cells in obese–overweight hemophilics. CD4+ lymphocytes, iNKT, γδT cells, and Tregs (CD4+ and CD8+), are significantly decreased in patients with hemophilia. Depletion of Tregs is more important in patients with factor VIII inhibitor. Physicians caring for hemophilia patients should realize that, even when they are not suffering infections frequently, may have early evidence of cellular immunodeficiency.